Michael Phelps began the final chapter of his storied career with a golden hue on Sunday as he helped the U.S. men's team to victory in the 4x100 metres freestyle relay to collect his 23rd Olympic medal.However, there were heartbreaks in tennis as world No.1 Novak Djokovic departed the Gam

Michael Phelps began the final chapter of his storied career with a golden hue on Sunday as he helped the U.S. men's team to victory in the 4x100 metres freestyle relay to collect his 23rd Olympic medal.

However, there were heartbreaks in tennis as world No.1 Novak Djokovic departed the Games in tears. Williams sister -- Serena and Venus -- too bowed out of women's doubles event.

Phelps took the second leg after Caeleb Dressel led off for the Americans, and it was another memorable performance at a distance that isn't Phelps' specialty. His split of 47.12 seconds gave the Americans a lead they never relinquished. In fact, it was a faster time than all but the three anchors on the medal-winning teams.

Ryan Held protected the top spot before handing off to Nathan Adrian, the top sprinter in America. It was never really in doubt at that point, as Adrian touched first in 3 minutes, 9.92 seconds. Defending Olympic champion France took the silver in 3:10.53, while Australia rallied for the bronze in 3:11.37.

ADAM PEATY, KATIE LEDECKY BREAK RECORDS

Another day, another world record for Britain's Adam Peaty at the Rio Olympics.

Peaty took gold in the men's 100-meter breaststroke Sunday night with a time of 57.13 seconds, shattering the mark of 57.55 he set one day earlier in the preliminaries.

Peaty cruisied away from Cameron va der Burgh of South Africa, the defending Olympic champion who took silver this time in 58.69.

The bronze went to Cody Miller of the United States, whose time of 58.87 held off teammate Kevin Cordes.

Top-ranked Novak Djokovic was swept out of the Olympic men's singles tennis tournament in the first round Sunday by the 2009 U.S. Open champion 7-6 (4), 7-6 (2). Because of three left wrist surgeries, del Potro is ranked just 145th in the world. But when the Argentine is healthy and smacking his signature forehand around the court, his play is worthy of the gold medal match.

It was a raucous atmosphere in the last match of the night on center court, where del Potro fans chanted for him and Brazilians would try to drown out their rivals with cheers for Djokovic.

With the loss, Djokovic is still left seeking his first Olympic gold medal.

The result in Brasilia leaves Brazil tied for second place in Group A, in need of a victory in the final game, against Denmark on Wednesday in Salvador, to advance to the next round and avoid another embarrassing elimination at home two years after the 7-1 loss to Germany at the World Cup.

Neymar, the tournament's biggest star, played below expectations for the second straight game, and young strikers Gabigol and Gabriel Jesus also struggled.

Upset fans chanted "Marta, Marta," in reference to the five-time world player of the year who has been thriving with the women's national team.